[ VOLUME 2 I ISSUE 3 I JULY – SEP. 2015 ]
E ISSN 2348 –1269, PRINT ISSN 2349-5138
PID Tuning of Automatic Voltage Regulator
Piyush Mathur
M.Tech Scholar
Deptt. of Electrical Engineering
J.N.U., Jodhpur.
Shyam K Joshi
Asst. Professor
Deptt. of Electrical Engineering
V.I.E.T., Jodhpur
Received July 02, 2015
Accepted July 25, 2015
ABSTRACT Automatic voltage regulation is an important study concerning the
variation in rated voltage due to inductive and capacitive loads. Inductive loads leads to a
voltage drop and capacitive load leads to a voltage rise and result in variation of voltage
from its rated value. For satisfactory working of various electrical appliances, regulation in
voltage is very much important, the prescribed limit for voltage variation is within (
of its normal value, so that consumer’s equipment operate satisfactory [1]. It is therefore, in
present work we have designed automatic voltage regulator using MATLAB simulink and
evaluated its performance with PID controller. The controller has been tuned using ZN
closed loop Tyerus-Luyben and Astrom Hugglund methods, Singular Frequency method
and IMC method. It has been observed that Tyerus-Luyben based PID controller gives the
best performance among these controllers to improve the dynamic response, reduced
transient and eliminate the steady state error with in minimum time. The comparative
study of different PID tuning methods for automatic voltage regulation is main outcome of
this paper.
Key words : Automatic Voltage Regulator (AVR), Automated PID Tuning, SISO, TyerusLuyben (TL), Astrom Hugglund (AH), Singular Frequency (SF) and Internal Model Control
(IMC).
1. Introduction of Automatic Voltage Regulator
A
voltage
to
output voltage of the generator increases or
automatically preserve a constant voltage
decreases accordingly. The AVR calculates
level. A voltage regulator may be a simple
how much voltage has to be sent to the
"Feed forward" design or may include
exciter numerous times a second, therefore
negative feedback. It may use an electro-
stabilizing
mechanical,
components.
predetermined set point. When two or more
Depending on the design, it may be used to
generators are powering the same system
regulate one or more AC or DC voltages. In
(parallel
the first consign the AVR monitors the output
information
voltage and controls the input voltage for the
equivalent all output.
exciter of the generator. By increasing or
2. AVR Theory and Controller Design
decreasing the generator control voltage, the
We have designed the AVR using first order
18
regulator
or
is
electronic
designed
IJRAR- International Journal of Research and Analytical Reviews
the
output
operation)
from
voltage
the
more
AVR
to
a
receives
generators
Research Paper
to
[ VOLUME 2 I ISSUE 3 I JULY – SEP. 2015 ]
E ISSN 2348 –1269, PRINT ISSN 2349-5138
transfer function model of Amplifier, Exciter
P, I, and D. Simply these values can be
and Generator. The simulink is given in Fig.1.
interpreted in terms of time, P depends on
also its natural output on unit step input is
the present error, I on the accumulation of
shown in Fig.2.
past errors, and D is a prediction of future
errors, based on current rate of change. The
proportional,
integral,
and
derivative
conditions are summed to calculate the
output of the PID controller.
Defining u(t) as the controller output, the
Fig.1. Simulink for AVR
final form of the PID algorithm is
Where,
MV=manipulated variable
U (t) =controller output
variable of integration
e=error
Kp- proportional tuning parameter
Ki- proportional tuning parameter
Kd- proportional tuning parameter
Fig.2. Output of AVR
t= instantaneous time
3. PID Tuning of AVR
Proportional-integral-derivative
controller
3.1 PID Controller for AVR
(PID controller) is a controller widely used
The AVR with PID Controller is given in
in
Fig.3.
industrial
control
systems.
A
PID
controller calculates an error value as the
difference between a measured process
variable and a desired set point. The
controller attempts to minimize the error by
adjusting the process through use of a
manipulated variable. The PID controller
algorithm involves three separate constant
Fig.3. AVR with PID Controller
parameters, and is accordingly sometimes
We have used SISO design tool & automated
called three-term control: the proportional,
PID tuning to tune the PID controller for AVR.
the integral and derivative values, denoted
Research Paper
IJRAR- International Journal of Research and Analytical Reviews
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[ VOLUME 2 I ISSUE 3 I JULY – SEP. 2015 ]
E ISSN 2348 –1269, PRINT ISSN 2349-5138
The basic steps of SISO design and automated
Step-4:- Select blocks and tune PID block
PID tuning are given below.
now open design configuration wizard.
3.2 SISO Design (Single Input Single
Step-5:- Select step analysis plot.
Output (SISO) Design Configuration)
Step-6:- Click finish automatically open
The SISO design task includes several tools
for tuning the response of SISO systems:
1. A graphical editing environment in the
SISO design tool window that contains
design plots such as root-locus, and Bode
diagrams etc.
SISO design task.
Step-7:- Select Automated tuning and now
selects PID tuning methods.
4. Simulation Results
(A) Z-N Tyerus-Luyben Method
The output response of Automatic voltage
regulator with ZN-TL method is shown in
2. An LTI Viewer window where you can
Fig.4.
view time and frequency analysis plots of
the system.
3. Compensator editors where one can
directly edit the block mask parameters or
the poles and zeros of compensators in
your system.
4.
Optimization-based tuning methods that
automatically tunes the system to satisfy
5.
Fig.4. Output of AVR by ZN T-L method
design requirements.
(B) Z-N Astrom Hugglund Method
A tool that automatically generates
The output response of Automatic voltage
compensators using PID tuner which
regulator with ZN-AH method is shown in
cover following tuning methods viz
Fig.5
Internal Model Control (IMC), ZN-TL, ZNAH, Singular frequency [4].
3.3 Steps for Automated PID tuning
Step-1:- In MATLAB after design the block
diagram selects tools.
Step-2:- Select Control Design from tools.
Step-3:-
In
control
design
select
compensator design and open control and
estimation manager.
20
Fig.5. Output of AVR by ZN A-H method
IJRAR- International Journal of Research and Analytical Reviews
Research Paper
[ VOLUME 2 I ISSUE 3 I JULY – SEP. 2015 ]
E ISSN 2348 –1269, PRINT ISSN 2349-5138
(C) Singular Frequency (SF) Method
(D) Internal Model Control (IMC) method
The output response of Automatic voltage
The output response of Automatic voltage
regulator with Singular frequency is shown in
regulator with IMC method is shown in Fig.7.
Fig.6.
Fig.7. Output of AVR by IMC method
Fig.6. Output of AVR by SF method
4. Tuning Results
Comparative study of PID controller use for Automatic voltage regulator shown in Table-1
Table-1
Tuning
Kp
Ki
Kd
Mp
Tr
Tp
Ts
Without PID
-
-
-
.4
.5
.9
15
ZN T-L
2.1
1.99
0.1
0.3
0.5
0.7
6
ZN A-H
1.3
5.34
0.08
0.81
0.6
0.8
11
SF
1.2
0.99
0.2
0.1
1
1.1
6.5
IMC
0.08
0.08
0.001
0.02
1.8
2.1
7
Controller
Conclusion - In this paper, we have given a comparative study of tuning of PID controllers to
achieve automatic voltage regulation. We have modeled PID controlled AVR system using
MATLAB simulink, SISO compensator design tool and automated PID tuner. We have tuned the
PID controller for AVR system using different methods like ZN-Tyerus Luyben, ZN-Astrom
Hugglund, Singular frequency and Internal model control. It has been observed that ZN- Tyerus
Luyben tuner gives best results among listed method. It gives minimum transient and settles in 6
seconds after the disturbance, which is best performance among all.
Research Paper
IJRAR- International Journal of Research and Analytical Reviews
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[ VOLUME 2 I ISSUE 3 I JULY – SEP. 2015 ]
E ISSN 2348 –1269, PRINT ISSN 2349-5138
Future Scope -This work can be further extended by using non-linear analysis method to study
Automatic Voltage Regulator (AVR).
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Research Paper